Disease Warning Signs & Early Detection

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson we'll go over the common types of diseases found in human populations, like infectious diseases, cardiovascular disease, and cancer. We'll discuss the warning signs for these diseases and the benefits of early detection.

What Is Disease?

One day coming home from school, you notice that your throat feels sore. Maybe you feel tired. Was it from yelling to your friends across the room, or did you stay up too late? At what point is it time to see a doctor? Sometimes an illness resolves on its own, but other times symptoms like this can indicate that something more serious is going on. Today, we'll be looking at some of the warning signs of common diseases and the benefits of early detection.

Infectious Disease

Infectious diseases are diseases that are communicated from person to person through the air in saliva droplets (like the flu) or through blood, vaginal fluid, or semen (like sexually transmitted diseases). Although some infectious diseases, like the common cold, resolve easily, others can cause serious damage to the body and even death. Human immunodeficiency virus, or HIV, is a sexually transmitted disease that invades the immune system. It attacks and kills T-cells, a special type of immune cell that fights off infections. Without T-cells, the body is very susceptible to other illnesses and HIV patients often die from secondary infections like pneumonia.

The early warning symptoms of HIV are similar to the flu and include fever, rash, chills, muscle aches, fatigue, and night sweats. If you are sexually active, it's important to get tested regularly for HIV, regardless of whether you experience these symptoms. But if you have recently had unprotected sex and start developing these symptoms, it's important to see your doctor right away.

Early symptoms of HIV infection
HIV symptoms

Early detection of HIV is crucial to fight off the disease. There is currently no cure and treatments, such as anti-retroviral therapy, a combination of drugs that kills viruses, can only stop the progression. Treatment can drastically improve the lifespan of the patient and help keep the immune system strong enough to fight off other infections.

Cardiovascular Disease

Cardiovascular disease is any disease that affects the blood vessels or the heart. There are many types of cardiovascular disease and most develop slowly over time, so prevention and early detection can be quite successful. One of the most common diseases is atherosclerosis, where the arteries fill with a fatty substance called plaque and become narrower. Usually there aren't any early warning signs for atherosclerosis until a serious medical event, like a heart attack, happens.

Atherosclerosis happens when plaque builds up in the arteries

Atherosclerosis happens gradually over time and can be caused by an unhealthy lifestyle, lack of exercise, and high levels of blood cholesterol. During your annual physical, a doctor will check your cholesterol levels and can see if you are at risk for atherosclerosis. If you are at risk, you may need to see a cardiologist, a heart doctor, who will listen to your heart for sounds that indicate your arteries are clogged and examine the electrical signals in your heart.

An EKG exam measures the electrical signals in the heart

If atherosclerosis is detected early, diet and lifestyle changes might be enough to reduce your risk factor and avoid surgery. Eating a diet low in saturated fat and rich in heart-healthy fats that come from olive oil, avocados, and nuts can be a great start. It's also helpful to exercise more often, which helps you maintain a healthy weight and can decrease stress.


Cancer is the process of uncontrolled cell growth. Cells that were once normal undergo mutations to their DNA, which changes how they behave. The cancerous cells grow out of control, crowding out the healthy cells in an organ and keeping them from doing their jobs. With no healthy cells to do the job of the organ, the organ fails and the patient dies.

Cancer progresses as cells divide more and more out of control
cancer progression

The warning signs of cancer vary depending on where the cancer is. The cancer might grow and press against nerves or blood vessels, which would cause tingling or numbness. Some cancers might be felt as a lump or growth, like breast cancer. Skin cancer sometimes forms moles or abnormal growths on the skin in early stages.

With such diverse symptoms, identifying cancer is tricky. The earlier cancer is detected, the easier it is to treat. If the mass is still small, it is much easier to treat than if it has grown and spread to different parts of the body. Regular exams can help you catch this disease early on.

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